The world’s oceans are in worse health than realised, scientists have said today, as they warn that a key measurement shows we are “running out of time” to protect marine ecosystems.
Ocean acidification, often called the “evil twin” of the climate crisis, is caused when carbon dioxide is rapidly absorbed by the ocean, where it reacts with water molecules leading to a fall in the pH level of the seawater. It damages coral reefs and other ocean habitats and, in extreme cases, can dissolve the shells of marine creatures.
Until now, ocean acidification had not been deemed to have crossed its “planetary boundary”. The planetary boundaries are the natural limits of key global systems – such as climate, water and wildlife diversity – beyond which their ability to maintain a healthy planet is in danger of failing. Six of the nine had been crossed already, scientists said last year.
However, a new study by the UK’s Plymouth Marine Laboratory (PML), the Washington-based National Oceanic and Atmospheric Administration and Oregon State University’s Co-operative Institute for Marine Resources Studies found that ocean acidification’s “boundary” was also reached about five years ago.
“Ocean acidification isn’t just an environmental crisis – it’s a ticking timebomb for marine ecosystems and coastal economies,” said PML’s Prof Steve Widdicombe, who is also co-chair of the Global Ocean Acidification Observing Network.
The study drew on new and historical physical and chemical measurements from ice cores, combined with advanced computer models and studies of marine life, which gave the scientists an overall assessment of the past 150 years.
It found that by 2020 the average ocean condition worldwide was already very close to – and in some regions beyond – the planetary boundary for ocean acidification. This is defined as when the concentration of calcium carbonate in seawater is more than 20% below preindustrial levels.
Washington, DC – U.S. Senators Sheldon Whitehouse (D-RI) and Lisa Murkowski (R-AK), and Representatives Chellie Pingree (ME-01) and James Moylan (R-GU) reintroduced the bipartisan, bicameral Coastal Communities Ocean Acidification Act. The legislation will strengthen coordination and collaboration between federal, state, local, and tribal entities on ocean acidification research and monitoring.
“The oceans are in trouble. Ocean acidification caused by carbon pollution is harming marine ecosystems and coastal industries like aquaculture,” said Whitehouse, Co-Chair of the Senate Oceans Caucus. “Our bipartisan legislation will assist in monitoring changes to the oceans and help us better understand how to protect Rhode Island’s blue economy from acidifying waters.”
“The impacts of ocean acidification on our coastal communities cannot be understated, particularly on our blue economy,” said Murkowski, Co-Chair of the Senate Oceans Caucus. “This legislation takes a holistic approach to understanding ocean acidification, encouraging experts from every walk of life to work together and ensure that our oceans stay healthy.”
The legislation would direct the National Oceanic and Atmospheric Administration (NOAA) to collaborate with and support state, local, and tribal entities that are conducting or have completed ocean acidification vulnerability assessments. The bill also strengthens partnerships between NOAA and a wide range of stakeholders involved in ocean acidification research, such as indigenous groups, coastal communities, state and local resource managers, fishery management councils and commissions, and the U.S. Integrated Ocean Observing System.
About thirty percent of carbon dioxide that is released into the atmosphere is absorbed by the ocean. The CO2 dissolves into seawater through a series of chemical reactions, increasing the overall acidity of the ocean. Increased seawater acidity hampers the growth and survival of young oysters and other shellfish by eating away at their shells. In 2017, Whitehouse conducted a science experiment on the Senate floor to show what happens when CO2 enters our oceans.
The Coastal Communities Ocean Acidification Act passed the House in the 118th Congress.
Shellfish aquaculture is a vital industry in the US, but one which faces mounting challenges threatening both productivity and business viability. Research often fails to align with growers’ immediate needs, so researchers set out to help close this gap in a new study published in Aquaculture Reports, interviewing over 30 commercial shellfish growers across the US Pacific region.
Funded as part of NOAA’s Ocean Acidification Program, former Research Scientist at the University of Washington School of Aquatic and Fishery Sciences (UW SAFS) and now a Fisheries Resource Management Specialist with NOAA Fisheries, Connor Lewis-Smith led the research to document how industry participants perceive ocean acidification threats and evaluate emerging adaptation strategies that are actively being researched: parental priming and native species portfolio diversification.
The research team included scientists from NOAA Northwest Fisheries Science Center (NWFSC), Puget Sound Restoration Fund, UW SAFS, and the University of the Virgin Islands. They interviewed owners, field managers, hatchery managers, and other staff from operations across five states on the Pacific Ocean: Washington, Oregon, California, Alaska, and Hawaii. “Operations ranged in scale and included hatchery, nursery, and growout components. We also included tribally managed and tribally affiliated businesses,” Lewis-Smith said.
Bird’s-eye view of an oyster farm (Connor Lewis-Smith).
Researchers have found that ocean acidification entered a “danger zone” in 2020, suggesting increased carbon dioxide levels have caused Earth to breach another planetary boundary.
The new study suggests our planet’s oceans are becoming too acidic to remain healthy. (Image credit: Philip Thurston via Getty Images).
Earth’s oceans are in worse condition than scientists thought, with acidity levels so high that our seas may have entered a “danger zone” five years ago, according to a new study.
Humans are inadvertently making the oceans more acidic by releasing carbon dioxide (CO2) through industrial activities such as the burning of fossil fuels. This ocean acidification damages marine ecosystems and threatens human coastal communities that depend on healthy waters for their livelihoods.
Previous research suggested that Earth’s oceans were approaching a planetary boundary, or “danger zone,” for ocean acidification. Now, in a new study published Monday (June 9) in the journal Global Change Biology, researchers have found that the acidification is even more advanced than previously thought and that our oceans may have entered the danger zone in 2020.
The researchers concluded that by 2020, the average condition of our global oceans was in an uncertainty range of the ocean acidification boundary, so the safety limit may have already been breached. Conditions also appear to be worsening faster in deeper waters than at the surface, according to the study.
“Ocean acidification isn’t just an environmental crisis — it’s a ticking time bomb for marine ecosystems and coastal economies,” Steve Widdicombe, director of science and deputy chief executive at Plymouth Marine Laboratory, a marine research organization involved in the new study, said in a statement. “As our seas increase in acidity, we’re witnessing the loss of critical habitats that countless marine species depend on and this, in turn, has major societal and economic implications.”
In 2009, researchers proposed nine planetary boundaries that we must avoid breaching to keep Earth healthy. These boundaries set limits for large-scale processes that affect the stability and resilience of our planet. For example, there are boundaries for dangerous levels of climate change, chemical pollution and ocean acidification, among others.
A 2023 study found that we had crossed six of the nine boundaries. The authors of that study didn’t think the ocean acidification boundary had been breached at the time, but they noted it was at the margin of its boundary and worsening.
Katherine Richardson, a professor at the Globe Institute at the University of Copenhagen in Denmark who led the 2023 study and was not involved in the new study, told Live Science that she was “not at all surprised” by the new findings.
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What causes ocean acidification?
Ocean acidification is mostly caused by the ocean absorbing CO2. The ocean takes up around 30% of CO2 in the atmosphere, so as human activities pump out CO2, they are forcing more of it into the oceans. CO2 dissolves in the ocean, creating carbonic acid and releasing hydrogen ions. Acidity levels are based on the number of hydrogen ions dissolved in water, so as the ocean absorbs more CO2, it becomes more acidic.
A scanning electron micrograph of Globorotalia tumida, a calcareous planktic foraminifera. This specimen was collected from IODP Site U1559 in the South Atlantic Ocean. Credit: Chris Lowery.
Between 252 and 66 million years ago, the ocean underwent a revolution.
That’s when plankton with calcium carbonate skeletons colonized the open ocean. When they died, their remains fell like snow over large parts of the seafloor. The abundance of their skeletons over time changed the marine landscape, leading to unique rock formations and vast deposits of carbonate rock.
This buildup of carbonate minerals was an important part of the Mesozoic Marine Revolution, or MMR — a period of transformation in Earth’s oceans that helped set the stage for today’s modern marine ecosystem.
According to a new study led by researchers at The University of Texas at Austin and published in the Proceedings of the Royal Society B: Biological Sciences, the change in calcium carbonate dynamics in the ocean appears to have influenced the evolutionary trajectory of tiny but mighty sea creatures: foraminifera.
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Forams can make their skeletons out of different materials, including sediments and organic matter. The researchers found that after the MMR, calcareous forams — which build their shells by secreting calcium carbonate — flourished, going on to become the dominant type of foram living today.
The study’s lead author Katherine Faulkner, who conducted the research when she was an undergraduate student at UT, said that in addition to shedding light on foram diversity through time, the findings could help researchers learn about how other forms of marine life responded to swings in ocean chemistry over geologic time.
Vertical distribution of seawater pH from the 3D gridded dataset. Credit: IOCAS
Ocean acidification, caused by the ongoing absorption of atmospheric CO₂, poses threats to marine ecosystems and biodiversity. Accurately assessing variations in seawater pH is crucial for evaluating biological responses to acidification and predicting the ocean’s capacity for carbon sequestration.
However, global ocean acidification has not been thoroughly studied due to sparse observations of seawater pH and inconsistent spatial coverage, especially at depths below the ocean’s surface.
To address these challenges, a research team from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) utilized a Stepwise Feed-Forward Neural Network (Stepwise FFNN) algorithm to identify the predictors that yielded the lowest reconstruction errors for seawater pH. Additionally, they integrated observational data from the Global Ocean Data Analysis Project (GLODAP) to create a global monthly 3D gridded pH dataset spanning the past 30 years.
“Our 3D gridded pH dataset extends to a depth of 2,000 meters and improves in both accuracy and reliability,” said Dr. Zhong Guorong, the first author of the study published in Earth System Science Data.
By categorizing global oceans into biogeochemical provinces based on pH drivers, the researchers optimized the selection of environmental variables, which enhanced the dataset’s accuracy. In addition, the use of cross-boundary optimal interpolation technology improved the accuracy of reconstructing marine chemical parameters.
Moreover, the pH dataset has been validated using a cross-validation method that reduces the risk of model overfitting, ensuring its reliability. The dataset is available to the public via the IOCAS Data Center, making it an essential resource for global climate modeling and marine conservation efforts.
The annually averaged global mean near-surface temperature in 2024 was 1.55 °C ± 0.13 °C above the 1850–1900 average. This is the warmest year in the 175-year observational record, beating the previous record set only the year before. While a single year above 1.5 °C of warming does not indicate that the long-term temperature goals of the Paris Agreement are out of reach, it is a wake-up call that we are increasing the risks to our lives, economies and the planet.
Over the course of 2024, our oceans continued to warm, sea levels continued to rise, and acidification increased. The frozen parts of Earth’s surface, known as the cryosphere, are melting at an alarming rate: glaciers continue to retreat, and Antarctic sea ice reached the second-lowest extent ever recorded. Meanwhile, extreme weather continues to have devastating consequences around the world.
In response, WMO and the global community are intensifying efforts to strengthen early warning systems and climate services to help decision-makers and society at large be more resilient to extreme weather and climate. We are making progress but need to go further and need to go faster. Only half of all countries worldwide have adequate multi-hazard early warning systems. This must change.
Investment in National Meteorological and Hydrological Services is more important than ever to meet the challenges and build safer, more resilient communities. Authoritative scientific information and knowledge is necessary to inform decision-making in our rapidly changing world, and this report provides the latest science-based update on the state of our knowledge of key climate indicators
Princeton University and Xiamen University researchers report that in tropical and subtropical oligotrophic waters, ocean acidification reduces primary production, the process of photosynthesis in phytoplankton, where they take in carbon dioxide (CO2), sunlight, and nutrients to produce organic matter (food and energy).
A six-year investigation found that eukaryotic phytoplankton decline under high CO2 conditions, while cyanobacteria remain unaffected. Nutrient availability, particularly nitrogen, influenced this response.
Results indicate that ocean acidification could reduce primary production in oligotrophic tropical and subtropical oceans by approximately 10%, with global implications. When extrapolated to all affected low-chlorophyll ocean regions, this translates to an estimated 5 billion metric tons loss in global oceanic primary production, which is about 10% of the total carbon fixed by the ocean each year.
The research is published in the journal Proceedings of the National Academy of Sciences.
Revealing critical insights into air-sea carbon dioxide exchanges, pH trends in the North Atlantic, and detailed observations in UK shelf seas, the study also details how ocean acidification impacts marine species through both direct physiological effects from changing pH and CO2 levels and indirect effects via food web disruption.
While some organisms like certain phytoplankton and seaweeds may show positive or neutral responses to elevated CO2, many marine invertebrates and fish species experience neutral or negative effects. Species that build calcium carbonate structures, including corals, shellfish, and important plankton groups, face particularly high risk. Even more developed organisms like fish, though less susceptible to direct impacts, could suffer from the loss of key prey species. The research highlights the need for better integrated approaches that scale from experiments to biogeochemical models. It also emphasizes the urgent need for enhanced observational capacity and improved model accuracy to better understand and address ocean acidification.
Atmospheric CO2 surpassed 420 ppm in 2024, continuing to rise by approximately 2.5 ppm annually over the past decade
The global ocean absorbs roughly 25% of anthropogenic carbon dioxide emissions each year
The North Atlantic Ocean, containing the highest levels of anthropogenic CO2 among ocean basins, is experiencing ongoing surface water acidification
Bottom waters in some locations are acidifying faster than surface waters
Certain marine species already show effects from ocean acidification during short-term fluctuations, potentially serving as indicators for long-term ecosystem impacts
Models project that continental shelf seawater pH will continue to decline through 2050, with rates increasing in the second half of the century depending on emissions scenarios
Coastal pH decline is projected to be faster in areas like the Bristol Channel compared to the Celtic Sea
Under high-emission scenarios, bottom waters on the North-West European Shelf seas could become corrosive to aragonite as soon as 2030
A fishing tender with 65,000 pounds of Bristol Bay red king crab arrives at Peter Pan in King Cove for processing in 2011. Photo by Margaret Bauman for The Cordova Times.
Ocean acidification appears to be a driver in the decline of Bristol Bay red king crab, a highly value wild Alaska seafood that has for years been threatened by climate change.
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A new report published on Feb. 7 in the Canadian Journal of Fisheries and Aquatic Science said that negative effects of acidification explained 21% of recruitment variability of Bristol Bay red king crab between 1980 and 2023, and 45% since 2000.
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“Anthropogenic emissions of carbon dioxide into the atmosphere have generated a substantial increase in ocean carbon uptake and a shift in the marine carbonate system to a state of higher acidity and lower carbonate saturation states in a process referred to as ocean acidification,” the report said. “Carbon dioxide is more soluble in cold water, and high-latitude waters that are naturally cold and carbon-rich, such as the Bering Sea, are particularly vulnerable to acidification.”
According to Darcy Dugan, director of the Alaska Ocean Acidification Network, these findings mark a shift in messaging from the research community.
“Prior to the study researchers believed species in Alaska were likely being impacted but we didn’t have the data or analysis to back it up,” she said. “Red king crab is the first species where we can see a correlation between acidity and the decline of a wild stock.”
Recent research reveals how fluctuations in storm season intensity can significantly influence ocean acidification (OA) conditions in the northern Strait of Georgia, located on the northeast Pacific coast. This area, characterized by weakly-buffered seawater, faced extreme OA characterized by multiple stressors, including calcite undersaturation, low pH, and elevated partial pressure of CO2 (pCO2) over three years.
The study, which utilized data from eight years of high-resolution monitoring at the long-term oceanographic station QU39, indicates stark shifts between storm seasons are pivotal for OA forecasting. The research highlights years characterized by weak storm activity, where OA conditions intensified, contrasting sharply with years of strong storms which led to healthier sea chemistry.
Researchers examined the interplay of factors leading to extreme OA, where variability in storm seasons plays a decisive role. During years with weaker storms, there was reduced conservative mixing and biogeochemical feedbacks, directly correlatively resulting in severe OA impacts. This correlation could provide predictive capacity for the coming years, illustrating the direct influence of environmental conditions on marine life vulnerability.
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Lead researcher Will Evans stated, “The emergence and abatement of corrosive conditions for calcite occurred not over extended chronologies, but rather during specific storm seasons, fundamentally reshaping the physical and biological underwater environments.” The conclusions drawn from this research underline the precarious state of the Strait of Georgia’s ecology as it grapples with anthropogenic changes.
Exploring the biogeochemical indicators, the research pointed to significant increases of total dissolved inorganic carbon (TCO2), impacting the seawater’s ability to buffer pH changes, highlighting how weakly-buffered settings are less resilient to both gradual and sudden changes.
Overall, this study not only documents the vulnerability of the northern Strait of Georgia but also emphasizes the immediate need for thorough monitoring and evaluation of coastal ecosystems as they adjust to changing climate conditions.
Dr. Emily Hall researching ocean acidification and climate change conditions on corals using a sea anemone as the model organism in the OASys lab on Tuesday, March 21st, 2017.
A pioneering study led by Mote Marine Laboratory, in collaboration with the Florida Fish and Wildlife Conservation Commission-Fish and Wildlife Research Institute (FWC-FWRI) and the U.S. Geological Survey (USGS), has uncovered a potential critical link between harmful algal blooms (HABs) and acidification in Florida’s estuaries.
The study reveals that distinct acidification events occurred following red tide blooms, and the growth of Karenia brevis (commonly referred to as Florida red tide) may contribute to ocean acidification and significant changes in water chemistry. This finding underscores the need for continuous monitoring to better understand and manage the interaction between HABs and acidification in coastal ecosystems.
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By analyzing the growth and decomposition of algal cell communities during blooms, the study revealed that biological processes play a significant role in altering water chemistry. These processes can sometimes intensify water acidity, a phenomenon closely tied to harmful algal blooms.
“This study highlights the importance of understanding how elevated CO2 affects red tide growth in natural ecosystems,” said Dr. Emily Hall, Senior Scientist and Manager of Mote’s Ocean Acidification Research Program. “By doing so, we can better anticipate and mitigate the impacts of harmful algal blooms on coastal communities.”
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By analyzing how red tide affects water chemistry, researchers have provided valuable insights into the biological and chemical processes driving acidification. Seasonal changes, such as increased carbon and alkalinity during dry periods, further emphasize the complexity of these interactions.
“Our study clearly highlights the important link between red tide and ocean acidification, but also indicates a need for much more clarity on the impacts of this connection,” said Dr. Michael P. Crosby, President and CEO of Mote Marine Laboratory. “Continuous sampling and sensor deployment are essential to understanding the relationship between K. brevis and acidification.”
The findings highlight the critical need for adaptive management strategies to protect Florida’s estuaries from the dual threats of harmful algal blooms and acidification.
Scientists at Yale and in Singapore have devised what may be the ultimate acid test — a comprehensive model for estimating the origins of Earth’s habitability, based in part on ocean acidity.
The new theoretical model applies previously published, Yale-led research to a wide range of interconnected geological and atmospheric processes. It may provide the clearest picture yet of how Earth evolved to a point where life was able to flourish.
“This is a tour-de-force theoretical endeavor, bridging a longstanding gap between surface processes and processes deep in the Earth,” said Jun Korenaga, a professor of Earth and planetary sciences in Yale’s Faculty of Arts and Sciences, and co-author of a new study in the journal Nature Geoscience. “This work presents by far the most comprehensive whole-Earth system model to estimate how ocean pH likely evolved during Earth’s history.”
The term pH (“potential of hydrogen”) is a measure of the concentration of hydrogen ions in an aqueous — watery — solution. A lower pH level equals higher acidity. A solution with a pH lower than 7 is considered acidic; modern-day seawater has a pH of about 8.
But it is widely believed that Earth’s ancient ocean was much more acidic, making it harder to sustain life. Many scientists have found that the synthesis of organic molecules is extremely difficult in environments with a pH level lower than 7.
El Cambio Global ha generado múltiples impactos en los ecosistemas marinos, desde la elevación del nivel del mar, hasta el aumento en la frecuencia de eventos climáticos extremos. Sin embargo, entre ellos la acidificación del océano (AO) sigue siendo un fenómeno poco comprendido a pesar de sus graves consecuencias para los ecosistemas y recursos marinos. Producida por la absorción de dióxido de carbono generado por actividades humanas, la AO altera la química del agua, dificultando la formación de conchas y estructuras calcáreas en muchas especies marinas, afectando directamente la acuicultura. En particular a bivalvos como choritos y ostiones, que podrían ver comprometida su calidad comercial debido a cambios en su color, tamaño, textura y valor nutricional, entre otros atributos.
Frente a esta problemática, un equipo de investigadores del Instituto Milenio en Socio-Ecología Costera (SECOS), la U. Católica de la Santísima Concepción, la Universidad del Desarrollo, y el Centro de Ecología Aplicada y Sustentabilidad (CAPES), entre otras instituciones, llevó a cabo un estudio publicado en la revista Future Foods. Utilizando técnicas de Preferencias Declaradas, los investigadores diseñaron un experimento para evaluar cómo la entrega de información sobre la AO podría influir en las decisiones de compra de los consumidores.
El estudio reveló que los consumidores prefieren productos con una “buena apariencia”, caracterizada por un color uniforme, ausencia de epibiontes [ciertos organismos pegados a la concha] y sin quiebres en la concha. Además, valoran la composición nutricional al momento de tomar una decisión de compra. “Justamente este es un atributo que será modificado por el cambio global, donde hemos observado una disminución en ácidos grasos, minerales, proteínas y vitaminas”, señala Valeska San Martín, investigadora del Centro de Investigaciones Costeras de la U. de Atacama y también del SECOS. La investigación además indicó que, cuando los consumidores reciben información sobre la AO, tienden a elegir el “mejor producto” disponible en el mercado, influenciados por factores como calidad, conveniencia personal y valor.
Unlike many vertebrates, oysters do not possess fixed sex chromosomes that dictate whether they develop as male or female at the moment of fertilization. Instead, they utilize a sophisticated biological mechanism known as environmental sex determination, where the surrounding environmental conditions influence their sexual development. Previous investigations have largely concentrated on factors such as temperature and food availability as drivers of sex ratios within aquatic populations; however, the role of fluctuating pH levels remained largely unexamined until now. The recent study led by researchers Xin Dang and Vengatesen Thiyagarajan breaks new ground in understanding how ocean acidification might modify the sex ratio of oysters across multiple generations, both in controlled hatchery environments and in natural habitats.
In their experiment, the researchers began with a collection of wild oysters to serve as the foundational population for their study. These oysters were divided into two groups, one maintained in water with a neutral pH and the other introduced to conditions simulating ocean acidification, characterized by a slightly more acidic pH. The results of this initial phase were revealing. The offspring of oysters that were spawned in the acidic environment exhibited a significantly higher ratio of females to males compared to the offspring of those raised in a neutral pH tank. This implies that the acidification of ocean waters could skew reproductive outputs towards female progeny, potentially altering population structures over time.
The follow-up experiments were equally illuminating. The second-generation oysters from the acidic environment were transplanted into two contrasting natural settings: one with a neutral pH and another with an acidic pH. Remarkably, regardless of whether these third-generation oysters were placed in an acidic or neutral pH habitat, they still exhibited an increased female-to-male ratio. This observation strongly suggests that the effects of ocean acidity on sex determination are not merely a transient phenomenon; rather, they can persist across generations. Such findings provide deeper insights into the transgenerational impacts of environmental stressors on marine life.
Recent research indicates a delayed onset of ocean acidification in the Gulf of Maine due to complex water mass interactions and temperature variations. The Gulf of Maine, significant for its ecological and economic value, particularly for fisheries, has become the focus of increasing scrutiny due to concerns about rising atmospheric CO2 levels affecting marine life。
The study reveals a surprising trend: seawater pH levels were low (~7.9) for much of the last century, but increased by +0.2 pH units over the past 40 years, contradicting the rising levels of atmospheric CO2. This unexpected increase raises questions about the factors influencing coastal water chemistry and the potential impacts on marine species.
Conducted by researchers including J.A. Stewart, B. Williams, and M. LaVigne, the study spans pH records from 1920 to 2018 CE, primarily focusing on changes noted from 1980 to 2000 CE. The researchers employed boron isotope measurements from long-lived coralline algae to create proxy records indicating seawater pH trends.
Significantly, the researchers highlight the remarkable interplay between different water masses within the Gulf of Maine. The influx of warmer, higher alkalinity waters derived from the Gulf Stream contributed to the increased pH, acting as a buffer against ocean acidification’s effects.
Coastlines face growing threats as climate change accelerates. Research from the University of Prince Edward Island warns that warming waters, ocean acidification, sea-level rise, and erratic rainfall are driving coastal ecosystems toward irreversible changes.
Critical habitats like mangroves, coral reefs, and wetlands, which protect against storms and support fisheries, are at risk of steep decline.
Global data reveals that heatwaves, shifting storm patterns, and disrupted river flows are pushing these ecosystems to the brink, threatening their stability and identity.
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Ocean acidification and brittle defenses
Oceans absorb carbon dioxide, becoming more acidic and making it harder for shellfish, corals, and some plankton to grow. Weakening these creatures means less food for predators and fewer stable habitats.
Laboratory work and field studies show that corals already struggle with bleaching and diseases when seas heat. Acidified waters add another layer of stress by reducing their ability to build and maintain reef structures.
According to the Pew Charitable Trusts, “unless global climate change is curbed, some of the world’s most productive coastal habitats could be irreversibly transformed.”
This spells trouble for communities relying on reefs for coastal protection, tourism, and sustenance.
Climate shift and coastal currents
With more intense hurricanes and unexpected winds, coastal habitats must work harder to recover from pounding waves and scoured seabeds.
Extreme storms can break coral skeletons, uproot mangroves, and bury seagrasses under sediment.
NOAA notes that “coastal ecosystems are on the frontline of climate change, with rising seas, warming waters, and coastal acidification already impacting fisheries, wetlands, and coral reefs.”
If protective habitats vanish, shorelines will feel the full brunt of storms. Altered ocean currents and changed upwelling patterns can also redirect nutrient flows, starve certain zones of essential ingredients, and shift fish stocks away from regions that depend on them.
Adding local fuel to the fire
Coastal development, runoff, and unsustainable fishing make climate problems worse. By degrading water quality, removing natural buffers, and altering sediment flows, human actions reduce the resilience of coastal habitats.
WWF’s Living Blue Planet report states that “climate change is affecting coastal systems at all levels — from coral reefs to Arctic ice-edge zones — and urgent action is needed to preserve these essential ecosystems.”
When layered on top of warming, acidification, and sea-level rise, these local pressures lock ecosystems into downward spirals.
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A call for climate coastal action
Halting greenhouse gas emissions is a big step. Reducing local stress — like runoff and destructive construction — helps too.
Many places already experiment with restoring marshes, planting mangroves, or opening fish passages in tidal zones. These steps buy time and boost resilience, but they are not a substitute for cutting emissions.
To keep vital resources intact, global and local efforts must move together. The sooner we make changes, the better our odds of passing on healthy coastal ecosystems to future generations.
The eastern Bering Sea is a highly productive marine ecosystem, supporting more than 40 percent of the annual commercial fisheries landings by volume in the United States. Scientists have developed new models that predict more extreme changes in this ecosystem by the end of the century. They anticipate larger summer northward shifts and changes (both increases and decreases) in the area occupied by important commercial crab and fish species.
Specifically, the majority of models estimate changes in the center of distribution for several commercially important species. They predict that most species’ summer distributions will shift north by between 50 and 200 kilometers by 2080-2089. Scientists also project:
Large declines in the amount of area occupied by red king crab and snow crab and potentially northern rock sole in the summer months.
A substantial increase in the area occupied by arrowtooth flounder, a key predator of walleye pollock.
Declines in probability of occurrence for most species in areas with low pH and oxygen concentration.
These changes are altogether more extreme than previous species distribution model projections, which accounted for fewer climate effects.
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Maps of two metrics of environmental novelty in the Bering Sea survey region for average temperature, pH, and oxygen conditions during 2040-2059 and 2080-2099, under each climate scenario (SSP 1-2.6 & SSP 5-8.5) and ESM (CESM, GFDL, & MIROC). Areas in gray are those for which temperature, pH, and oxygen are within the range of the average hindcasted conditions between 1995 and 2015. Areas in red / orange are those for which temperature, pH, and/or oxygen lie completely outside of the set of average conditions observed between 1995 and 2015. Areas in blue / green are those for which temperature, pH, and oxygen lie inside the range of hindcasted conditions, but represent novel combinations of these covariates. For both metrics, brighter colors indicate more novel conditions.
New and Better Models to Anticipate Ocean Changes
Scientists built species distribution models for eight common and/or commercially important species of groundfish and crabs in the eastern Bering Sea (adults and juveniles). These include walleye pollock, Pacific halibut, Pacific cod, arrowtooth flounder, northern rock sole, yellowfin sole, snow crab, and red king crab.
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To date, most studies projecting marine species distributions rely principally on temperature and static habitat characteristics such as depth. This can potentially lead to significant underestimation of species vulnerability to climate change.
However, for this study, ecologists combined 40 years of scientific surveys with a high-resolution oceanographic model. This model was adapted to the eastern Bering Sea by scientists at NOAA’s Alaska Fisheries Science Center as part of the Alaska Climate Integrated Modeling project. They examined the effects of bottom temperature. But they also incorporated information on oxygen, pH, and a regional climate index (the extent of the eastern Bering Sea “cold pool”). They considered all of these factors to produce a range of different climate projections through the end of the century. Model projections also anticipated warming under both low and high greenhouse gas emission scenarios.
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Oxygen and pH
The oceans absorb about 30 percent of global carbon dioxide emissions, and warmer water holds less oxygen. Climate change is also leading to the acidification of deoxygenation of much of the global ocean. All animals need oxygen to survive, and many species are expected to shift towards deeper, cooler waters to keep up with climate change. Lower dissolved oxygen content at depth may constrain their ability to do so. Reduced pH in water has the potential to impair organisms by changing their metabolism and physiological function. For crabs and other calcifying organisms, it can decrease calcification and shell formation rates.
Yet, few studies projecting future changes in species distributions integrate the effects of oxygen and pH. In many cases, these variables are not available to modelers, but recent advances in oceanographic modeling have made it possible to include their effects.
The authors found that the estimated effects of oxygen and pH were largely consistent among species. Where environmental oxygen and pH levels were lower, groundfish and crabs were less likely to be observed in scientific surveys. However, they also found the effects of oxygen and pH were difficult to disentangle using survey data, so they modeled their effects using separate models. In projecting future climate-driven changes in species distributions, they gave more say to models that did a better job reproducing past trends.
Where Scientists Hope to Go Next with this Research
These results build on—and in many cases agree with—previous distribution modeling efforts in the Bering Sea. However, they demonstrate that models that account for factors beyond temperature can result in more pronounced range shift projections.
“What’s really exciting about this research is we are now able to construct long-term species range forecasts, which incorporate a wider array of climate impacts,” said Kirstin Holsman, co-author and research fishery biologist, Alaska Fisheries Science Center.
In future work, species distribution models may be used to improve the representation of species interactions in multispecies stock assessment models. Scientists also hope to be able to produce short-term forecasts and long-term projections that incorporate a better understanding of predator-prey overlap.
Antarctica is approaching a series of cascading tipping points that could reshape ecosystems and intensify global climate disruptions, according to a new study by an international team of scientists, including researchers from the University of Tasmania.
The study identifies eight potential tipping points spanning physical, biological, chemical, and governance systems. The research is published in the journal Ambio.
These include collapsing ice sheets, invasive species, ocean acidification, and pressures on the Antarctic Treaty System (ATS), which oversees human activity in the region.
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The study warns that these tipping points are interconnected, creating a risk of cascading effects.
Melting ice sheets, for example, not only contribute to sea-level rise but also disrupt ocean circulation, which is crucial for transporting heat, carbon, and nutrients around the globe. Such disruptions threaten marine ecosystems, global fisheries, and food security.
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At the same time, the Southern Ocean’s ability to absorb carbon dioxide—a crucial buffer against global warming—is diminishing.
“The interconnected nature of these systems means small failures can quickly escalate,” Professor King said. “Without decisive action, we risk triggering a chain reaction with far-reaching and irreversible consequences.”
The researchers call for stronger international cooperation, urgent climate policies, and greater investment in Antarctic science. Their findings frame Antarctica not as a remote and isolated region, but as a critical player in the Earth’s environmental systems.
The rise in carbon dioxide (CO2) levels in our world’s atmosphere is fueling an environmental threat to marine life. Ocean acidification is growing in magnitude as it moves into deeper waters.
Jens Müller and Nicolas Grube are environmental physicists in the Institute of Biogeochemistry and Pollutant Dynamics at ETH Zurich. They set out to investigate the consequences of acidification by developing a 3D model of our oceans.
The research, recently published in the journal Science Advances, sheds light on how ocean acidification has intensified since the industrial revolution kicked off.
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Mapping ocean acidification depths
Müller and Grube carefully designed an experiment to untangle the spread of ocean acidification.
Their focus: How deep down has acidification seeped into our oceans over time? To answer this, they developed an ocean model simulating the effects of rising atmospheric CO2 levels.
The model was based on historical data spanning over two centuries, with CO2 estimates for the years 1800, 1994, 2004, and 2014. This gave the researchers a timeline to monitor how acidification spread through the ocean layers.
Constructing the ocean model
Creating a model of this scale required careful planning. Starting with a standard ocean model that simulates water movement and chemistry, the researchers then added data points on CO2 levels and acidification indicators like proton concentrations, pH levels, and aragonite saturation states.
This comprehensive approach enabled the experts to accurately map acidification trends.
Acidification reaches new ocean depths
Ocean acidification is moving deeper into the ocean, with the average depth impacted by acidification measuring around 1,000 meters by 2014.
In regions influenced by the Atlantic meridional overturning current, acidification reached depths of up to 1,500 meters.
But this spread isn’t uniform; different ocean regions face varying levels of change due to factors like water circulation patterns and temperature.
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Future implications of deeper acidification
Müller and Grube’s findings emphasize the urgent need to address carbon emissions. As CO2 levels rise, ocean acidification will only get worse.
The deeper it goes, the harder it is to reverse the impacts. The long-term consequences for marine biodiversity and human communities relying on ocean resources are unclear.
Reducing carbon emissions will help slow acidification. Initiatives to shift to renewable energy, enhance energy efficiency, and promote conservation could also contribute.
